Overexertion injuries are the single largest classification of injury in construction, accounting for about 24% of all injuries. The goal of this project is to identify specific construction tasks which place craft workers at high risk for overexertion injuries and disorders. High risk tasks can then be identified so that ergonomic principles can be applied to modify the task or work environment to accommodate human capabilities and limitations. The specific aims of this project are to: 1. Develop a complete catalog of all construction tasks broken down step- by-step at the Basic Task Level according to the hierarchical taxonomy of construction field operations developed by Everett. 2. Analyze each task as a whole and each step of each task for the presence of the seven generic risk factors for overexertion injuries: repetitive exertions, static exertions, forceful exertions, localized mechanical stresses, posture stresses, low temperature, and vibration. 3. Use the above methods to identify several tasks which expose craft workers to the highest risks for overexertion injuries and develop workplace interventions to reduce ergonomic stresses for those tasks. 4. Quantify or measure the reduction of risk resulting from the interventions in #3 above as prototypes for widespread application of the knowledge gained in #1 and #2 above. We hypothesize that it is possible to identify the underlying causes of overexertion injuries for many specific construction tasks and that it is technically and economically feasible on many construction tasks to reduce the level of physical demands placed on craft workers. If the approach proposed in this project is successful in reducing overexertion injuries, the resulting knowledge would have widespread application in improving occupational health and safety, and expanding job opportunities for women, older workers, and construction workers who are partially disabled due to previously suffered overexertion injuries.